Contracts/Revive: caller_is_root does not return bool

[cmichi]

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Description of bug

In both pallet-revive + pallet-contracts the host fn caller_is_root returns u32, opposed as to what the comments state (bool):

polkadot-sdk/substrate/frame/contracts/uapi/src/host.rs

Lines 270 to 272 in 82117ad

	/// A return value of `true` indicates that this contract is being called by a root origin,
	/// and `false` indicates that the caller is a signed origin.
	fn caller_is_root() -> u32;

The analog function caller_is_origin returns bool for everything.

The host fn has already been stabilized for pallet-contracts and also implemented this way in hyperledger-solang/solang#1620 (cc @xermicus). So changing it for pallet-contracts is probably tricky, for pallet-revive it would be good though.

cc @athei

Steps to reproduce

No response

[athei]

This is just the uapi wrapper which returns the wrong type. The host function itself will always return 1 or 0 in the output register. This can be changed easily. Just an oversight.